Bacteria of the appendix. Scanning electron micrograph (SEM) of various bacteria found in the human appendix. The appendix houses a diverse community of bacteria, some beneficial and some potentially harmful. While its often thought of as a vestigial organ, research suggests it may play a role in gut health by harbouring a reservoir of beneficial bacteria that can be released to repopulate the gut during times of illness or antibiotic use. However, if the appendix becomes obstructed or inflamed, it can lead to appendicitis, an infection caused by the overgrowth of bacteria. Magnification: X 8000 when printed 10 centimetres wide.